For the given statements:
($$I.$$) $$\,\,\,$$ Mating spur gear teeth is an example of higher pair
($$II.$$) $$\,\,\,$$ A revolute joint is an example of lower pair.

Indicate the correct answer.

A 4-bar mechanism with all revolute pairs has link lengths $${l_f} = 20\,\,mm,\,\,{l_{in}} = 40\,\,mm,\,\,{l_{co}} = 50mm$$ and $${l_{out}} = 60\,mm.$$ The suffixes $$'f', 'in', 'co'$$ and $$'out'$$ denote the fixed link, the input link, the coupler and output link respectively. Which one of the following statements is true about the input and output links?

A slider-crank mechanism with crank radius $$60$$mm and connecting rod length $$240$$mm is shown in figure. The crank is rotating with a uniform angular speed of $$10$$ rad/s, counter clockwise. For the given configuration, the speed (in m/s) of the slider is ____________.

An offset slider - crank mechanism is shown in the figure at an instant. Conventionally, the Quick Return Ratio (QRR) is considered to be greater than one. The value of QRR is _______